Latest polls show Douglas Alexander, who had a majority of 16,614 at the last election, trailing the SNP by 11 points in Paisley and Renfrewshire South
Photograph: Murdo MacLeod for the Guardian

Labour’s Scottish leader Jim Murphy came face to face this week with the raw rage consuming Scotland. While out campaigning in the centre of Glasgow, a nationalist with a megaphone and a T-shirt emblazoned with the words “The Scottish Resistance” barracked him for being “a traitor to Scotland”. A passerby swore at him as he walked down the street. Another denounced him as a “red Tory”.

Eleven miles to the west of the city, in Paisley, his colleague, Douglas Alexander, campaign coordinator for Labour’s whole UK campaign, was faring little better. Labour volunteers report resistance among voters to even accepting party leaflets, treating its campaign literature as toxic. On doorsteps, disenchanted Labour voters are vehement they will never vote for the party again.

The disillusionment with Labour, evident during last year’s independence referendum, has turned into an absolute rage, one that Labour MPs frequently describe as bordering on the irrational. That rage could consume both Alexander and Murphy. Latest polls show Alexander, who had a majority of 16,614 at the last election, trailing the SNP by 11 points in Paisley and Renfrewshire South. In the neighbouring constituency, Renfrewshire East, Murphy, who had a majority of 10,420, is trailing nine points behind the SNP.

That there is even a question mark against their re-election shows how far and how abruptly Labour has declined in Scotland. Labour in 1987 won 50 of Scotland’s then 72 seats with a pool of talent that included John Smith, Gordon Brown, Robin Cook and Donald Dewar. On 7 May, it is in danger of being reduced to single figures at Westminster, a leaderless rump, a meltdown that could hasten Scotland’s eventual departure from the union.

Labour’s candidate Douglas Alexander is joined by former minister Alan Johnson campaigning in Paisley and Renfrewshire South. Photograph: Murdo MacLeod for the Guardian

Senior Labour figures in Scotland struggle to come up with consistent answers as to what has gone wrong. They offer explanations in private that range from the unpopularity of Ed Miliband - the renaissance of the last two weeks looks as if it has come too late – to the way many of the 45% who voted yes for independence, a large proportion of them Labour, have simply switched to the SNP. The sense of betrayal by David Cameron in the immediate aftermath of the referendum has not helped either.

Alexander, sitting in a cafe opposite his campaign headquarters in Paisley, described the referendum as a “seismic event” whose repercussions were still being felt, having generated deep personal questions about identity.

But he also took a wider view. “To understand what is happening here in Scotland you need to look more broadly across Europe, where nationalism has animated deep feelings following the financial crisis,” he said. “The financial crisis trashed people’s confidence in the powerful: not just regulators and bankers but also politicians. The [MPs’] expenses crisis deeply damaged people’s confidence in politicians’ motives.” The combination of the two had created “fertile territory for populist nationalism”.

Others argue that Labour’s problems predate this, that the party has been too complacent for too long, especially in the west of Scotland, where it was guilty of cronyism, putting forward nonentities as candidates for councils, the Scottish parliament and Westminster.

Gerry Hassan, co-author of The Strange Death of Labour Scotland, published in 2012, said the props that had sustained Labour in Scotland for so long – the almost century-long support of the Catholic vote, the high proportion of council houses and mass membership unions – have been removed. “That is dead politics now,” he said.

Hassan, an academic at the University of the West of Scotland, who left the Labour party after 24 years and has not joined another, said: “There is something going on now. This profound anger towards the Labour party.” Asked if it heralds a realignment of Scottish politics - in the way that the Conservatives, who had a majority in Scotland in 1955, have become marginalised - or is just cyclical, Hassan said bluntly: “It is not cyclical.”

There is a deep pessimism at the heart of the Scottish Labour party about what is going to befall it on 7 May. On a good day, one prominent party member said, they might hold on to a dozen or more seats, down from 41. On a bad day, the same source said, there could be only one Labour MP left north of the border, Willie Bain in Glasgow North East.

SNP membership, now at over 100,000, has surged while Labour’s has been in slow decline, with estimates ranging from 20,000 to as low as 10,000. Many of the new SNP recruits are from Labour. Tommy Sheppard, the SNP candidate who could take Edinburgh East from Labour - the Edinburgh Evening News front page this week claimed Labour was fac ing a wipe-out in the capital - was Labour’s assistant general-secretary in Scotland from 1994 to 1997 when Tony Blair became prime minister.

Sheppard said that Labour left him. Instead, he concentrated on the Stand comedy club he co-founded in Edinburgh. He came back to politics last year, joining the SNP.

Sheppard, who describes himself as a republican socialist democrat, not instinctively a nationalist, sees independence as a means to an end. “Knocking on doors I find people saying they will never vote Labour again,” he said. “I think there is a political realignment, a reconstitution of the politics of Scotland.”

Out on the stump with Nicola Sturgeon in Edinburgh’s Portobello area, Sheppard blamed Labour’s sharp decline in part on the way the party handled the referendum. “I am old enough to remember the Common Market vote in 1975,” he said. “There were Labour yes and Labour no votes but Labour tolerated dissent then. They bungled the independence referendum. A lot of Labour people voted yes and were demonised by the party.”

Alexander’s SNP opponent is Mhairi Black, a 20-year-old Glasgow University politics student. She comes from a leftwing family that would once have steered her towards Labour but both she and her father, Alan, joined the SNP in 2011. His disenchantment with the party can be traced back to the decision by Blair’s cabinet to build the Millennium Dome, which he regarded as an inappropriate way to celebrate the start of a new century.

“The Labour party I was taught about by my grandpa and my dad, I just don’t see that anymore,” Mhairi Black said. “The Labour party I was taught about had big names, intellectual giants, names I would take pride in like the Tony Benns, the Keir Hardies, even the Dennis Skinners. You do not see that level of imagination or hope, that passion, anymore.” For her, the SNP now occupies the space as the party of social justice.

Knocking on doors in one of the better-off parts of Paisley, a former mill town, she met with a largely positive response in an area that would once have been Labour or even Conservative.

In the spite of the polls, Labour campaigners express hope they can hold both Alexander’s and Murphy’s seats. They point to the large bloc of don’t knows and note that the polls only ask about party rather than individuals - both Alexander and Murphy have high name recognition and they hope this might be to their advantage. And they are looking for a boost if Ed Miliband’s bid for Downing Street becomes credible. There is also an element of desperation in Labour courting Conservative tactical votes in both constituencies to block the SNP.

If the SNP does end up holding the balance at Westminster, it might seem feasible in London that Labour would reach some accommodation with the nationalists, that they would find a way to rub along, in spite of Miliband’s robust rejection of any deals. But that does not take account of the poisonous mood in Scotland. The rage felt towards Labour in Scotland is matched by hostility towards the SNP among senior Scottish Labour politicians, a hatred that goes way back. They argue that Labour’s prospects of a revival in Scotland would be damaged by working with the SNP and this could prove suicidal.

“Nicola Sturgeon and Alex Salmond’s words have a lot more to do with campaigning than governing,” Alexander said. “They have spent their entire lives not trying to help the Labour party but to end the Labour party. So forgive my scepticism as to their latest overtures.”